Screening apparatus



'Mmh 2,1943. vBE /OWE 2,312,665

SCREENING APPARATUS Filed Se pt. so, 1940 Patented Mar. 2, 1943 w S WGWWW? Z 1 dpplication september at, 1940; sem1 No; 358,983,;

apparatus; it

My invention relates to screening more particularly to'apparatusforuseparatlnfl fronia continuously progressedrnass of p'articueg latematerial particles ofundesirable sizes shapes, and my invention hasfor.1an;objec t the V this character.

provision of efiicient and. reiiable apparatusioi Although apparatus enbodying invention is not limited thereto,'it"is particularly usefulinseparating particlesof slate or other unde sirable'substances from a'I'naSs'of coal. it ls common practice, in preparing various ,types: ofcoal for marketingwtoscreen the 'material: to t size-so as to providesubstantially uniform grades of coal, each'grade representing particlesof such' size as to pass through a selected screenhaving.

openings of the desired manimun size andffto be retained ,on a 'secondscreen having openings of V the desired minimum size.i' Although suchscreening operations are relatively efficient" ingradingthefcoal, it iswell known that underx sized particles of coal may remainineachgrade dueto theiact that it 1s uneconomical to carry the screening ope'rationibeyondsa 2 certain pointy 5 w and it is likewise ;well.known .that thevarious grades of coal, particularly whenfminedin'cer-I tain localities,will also contain afllarge number of pieces of relatively noncombustiblematerial such as slate or thelik e. These fpieces oi slate are usuallyrelatively flat as compared to' the substantially cubical fracture ofthe'coal." r The presence ofthese'so-called hats in themass of coal ishighly objectionable to thepun chaser, andiattempts have heretoforebeen'made to provide economical methods of removing such.-

flats. So far as I am awareghowever, '1 all such I1 "attempts have beenrelatively unsuccessfuland something is e f Ob desired n apparatus'oiflats-contained therein.-

I l In carrying out my invention in one form,

N f 331L 55,

shelves the shelves. being-arranged step-like relation The rnaterlal tobe vsclrfe'e:tied;is tibplled wt th u e v r n t he.ser ines e, m meansare fprovided for imparting thereto recurrent swoon which causestheniajtrial tq'pas from sheli to shelf downwardly ofithe screening 7element" The recurrent amotion imparted @to the screening elementiincludesa horizontal" reciproreating component' characterized; b h 7changes inrthe speedof'rnovement t atthepap ticles, which momentarilyscolnetq rest onftlje 1" shelves and. which .are ucharacterizedfby adimer 'sion smallerflthanithe' width or height of the slots, will bedischarged through the s1ots;4tne*move- 'ment caused byth e inertia ofthe particles.

Thus flats, which momentarily .rest on-the shelves 2.;

in fiatwise relation, are separated from the mass of coal-and thoseflats whilchnos not occupy such a position on3the. shelvespass downwardQto the, next shelf .where they J again; have] an 10 tion for"dischargel t I-Qfi hf the isljots. s 'j' fFor a more co' npleteunderstanding ofmy-invention;reference should' now be had to the d awinintvhichz I Fig, l 'isatop plan vie of bodying my invention;

a ap a us: am-

' Fig. 2 is an=elevational-vie 5 oi-theapparatus shown in Big; lzgan'd'3 a -fimfi et i taEi m ts iolifi view: showing a .p'ortion oi thecreening element. and illustrating; the manner in which the n flats arecaused topa'ss through the'slots'fsjyfas- 'ovin'g mass of to separatethe flats from the. .coal; v

ically; =.extend1n cross beam"Mis -Suitable diagonlzblaces 7 o be.provided for the" 'upright members provide a' screening apparatustowhichtnematerial to be screened mayQ-be continuously d elivered. and fromwhich' thef material, I after screening, is continuouslydischargdywhich" ap paratus comprises any inclined screening-'-elevme'nt having a plurality of transversely extend-- ing shelves withslots of predetermined size extending'along the rear edges oftheshelves. "In the preferredembodi'ment of. my invention these slotsconstitute the spaces between adjacent supported on the base l0;icomprises. *which-includes-apair:of1;sideimembers connected together;at-a'thelr.-;opposite nds byJ-s:

sho

i Z the screening 1 element; which is movably cross members I 5: and;16- r esp,e :tively..- Extend-V ing transversely-of the .frame iormedabyilthe N15,, and I [6,; Ifprovide 'a'f'pl uch abrupt V 'thed!&W1ng',TI1191173751 0 "my-invention as embodied in. a screening appa-:ratus. comprisinga; base; 1' ',adjacentone end with wirame comprising;a pair or enmarsupaag Li I V v connected together. at their I uppeflfend b "1a the: preferred embodiment of my gnvmion ing supporting frame.

between, each shelf being spaced forwardly of the one immediately aboveto provide a stepconveyor (not shown) or other receiving means.

As shown best in Fig. 2, the upper end of the screening element or frameis supported at each side on an adjustable hanger 2i, the'lower end ofeach of the hangers 2| being pivotally connected to a bracket 22 on theportion I6 of the screening element and the upper end of each hangerbeing pivotally connected to a bracket 24 secured to the cross bar [2 ofthe upstand- The screening element is thus supported in an inclinedposition but is free to move in a substantially horizontal directionrelative to the base l0.

While any suitable mechanism may be provided for imparting to thescreening element a recurrent motion of the character to be hereinafterdescribed, I have shown for purposes of illustration a mechanism whichcomprises a pair of springs 25 disposed on opposite sides of thescreening element and having their'respective opposite ends connected tothe base and to the members ll of the screening element. The operatingmechanism also includes an operating bar which, as shown, is pivotallyconnected at one end to the cross member and is provided at its oppositeend with a lug or cam follower 21 and adapted to be engaged by-arotatable cam 23 carriedon a, shaft 29, the shaft 29 being rotatablyiournalled in brackets 30 which extend rearwardly from the uprightsupporting members i I. In order to maintain the operating bar 26 andthe follower 21 in contact with the surface of the cam 28 at all times,suitable biasing means may be provided for the-bar 26, and for purposesof illustration I have shown a coil spring 40 associated with thepivotalconnection between thebar 2B and the cam member l5 for urging thebar 26 downwardly toward the cam.- The shaft 28 isadapted to bedriven'by any suitable powermeans (not shown) in a counterclockwisedirection, as indicated by the arrow in Fig. 2,

and the cam 28 is shaped to provide a gradually increasing radiusterminating in an abrupt shoulder 3|. 1

' In the operation of the apparatus thus far described, coal or othersuitable particulate material to be screened may be continuously fed tothe upper end of the screening element in any desired manner, and forpurposes of illustration I have shown a hopper 32 supported ontheupright frame formed by. the members H and [2. The coalissuingfrom-the lower end of a hopper 32 engages the flat end piece i6of the screening element and moves downwardly onto the uppermost ones ofthe step-like shelves I1. If it is assumed now that the shaft 29 isbeing rotated in the direction indicated, itwill .be apparent thatthe'cam 28 will act on the cam follower 21 to move the operating rod 26in a left-hand direction, whereupon the screening element moves in acorresponding direction, the upper end Hare spaced vertically to provideslots i8 thereswinging on the hangers 2| and the lower end sliding alongthe base 10. The sliding movement of the lower end is of course guidedby the track 19 in which the screening element rests.

In Fig. 3 I have shown the relationship which the particles of coal andthe flats may assume with respect to the shelf members I! as the mass ofcoal passes down the inclined screening element. As there'shown, certainof -the flats 33 will assume a flatwise position on the shelves l1,although others of the flats, for example the one indicated by thereference numeral 34, may be carried along with the particles of coal.As soon as the cam 28 is rotated to a position wherein the cam follower2'! passes over the abrupt shoulder 3!, the springs 25, having beenextended during the movement of the screening element in a left-handdirection, will abruptly move the screening element at a high speed in aright-hand direction. The abrupt initiation of this high speed movementwill cause the flats 33 (Fig. 3), by reason of their inertia, to bedischarged through the slots I8 at the rear edges of the shelves II. Thetrack IS in which the lower end of the screening element is guided isprovided at each side with inwardly extending portions 35 which arepositioned to be engaged by theends of the side members l4 andconstitute stops for the screening element which abruptly terminate thehigh speed movement of the screening ele-' ment under the force exertedby the springs 25. This abrupt termination of the high speed movementcauses the particles of coal 36 (Fig. 3) and those flats which have notbeen discharged through the slots l8, for example the flat 34, to movedownwardly over the shelves and it will be apparent that at .each suchmovement the flats remaining in the mass of coal will be given anadditional opportunity to assume a flatwise position on one of' theshelves l1, so that by the time. the mass of coal reaches the lower endof the screening element substantially all of the flats will have beenremoved. In addition to the flats,

it will of course be apparent that any particles of coal having adimension smaller than the height of the siots l8 will likewise beseparated from lustrated in the drawing is adaptedto provide a recurrentmotion characterized by an abruptly initiated and abruptly terminatedhigh speed movement, the abrupt initiation causing movement of the flatsthrough the slots and the abrupt termination causing progressivemovement of the mass of coal down the inclined screen, it will beapparent that various other sequences of movement may be employed solongas the movement of the screen is a recurrent movement characterized bysufficiently abrupt speed changes to effect the desired movement of theparticles with respect to the shelves l1.

Although the shelves ll may be of various widths and, if desired, maybe, arranged in exactly horizontal relation, I have found that excellentresults are obtained if the width of the shelves is only slightlygreater than the topsize of the graded coalto be treated. Furthermore,

Y I have found that movement of the'flats through the. spaces or slotsbetween the shelves l'I will be facilitated by arranging the shelves llwith a slight rearward inclination from the; horizontal, and in Fig. 3 Ihave shown the shelves as inclined from the horizontal by a small anglea. If desired, the shelves I1 may be so supported at their opposite endson the side members l4 as to provide for angular adjustment of theshelves to, vary the angle a if it is desired to changethe rearwardinclination of the shelves. Such adju'stment of the shelves I! will ofcourse alter the size of the slots I8, and in some cases it may bedesirable to change the inclination of the shelves without changing thesize of the 510125.

This may be accomplished by adjusting the hangers 2|, each of which isprovided as shown with a turnbuckle 23 which may be rotatedto lengthenor shorten the hangers 2| as desired; It. may also be desirable, uponadjustment of the hangers 2], to raise or lower correspondingly thehopper 32 and any suitable means (not shown) may be provided for thispurpose.

It will thus be seen that I have provided an apparatus which is ofexceedingly simple construction, involving only a few parts, and whichis effective in its operation to remove substantially all of the flatsfrom a continuously progressed body of coal during passage of the coalover a screening element having a predetermined recurrent motion.

While I have shown particular embodiments of my invention, it will beunderstood, of course, that I do not wish to be limited thereto sincemany modifications may be made, and I, therefore. contemplate by theappended claims to cover any such modifications as fall within the truespirit and scope of my invention.

Having thus described my invention, what I claim and desire to secure byLetters Patent is:

1. In a screening apparatus, the combination of a screening elementacross which the material to be screened passes during the screeningopera:

edges thereof and by an abrupt termination of said high speed forwardmovement to cause other portions of said material to be discharged fromthe front edge of each shelf member so as to be advanced down saidsteps.

2. In a screening apparatus, the combination of an inclined screeningelement over which the material to be screened passes during thescreening operation, said screening element including a plurality ofvertically spaced shelf members each of which is of a widthsubstantially equal to the maximum graded size of the material to be,screened and is positioned forwardly of the one above to provide aseries of steps having discharge slots therebetween of a height lessthan the minimum graded size of said material, means for supplying amass of the material to be screened to the upper portion ofsaidscreening element, and means for producing a recurrent motion ofsaid screening element, said motion producing means including means forabruptly initiating a high speed forward movement whereby pieces" ofsaidmaterial on said shelf members having at least one dimension smallerthan-thewidth of said discharge slots are discharged throughsaidslots,and means for abruptly terminating saidhigh speed movement wherebythe remaining material on said shelf members is discharged from theforwardedge of each shelf progressivelyto move said material down saidseries of steps.

3'. In a screening apparatus, the

edge of each shelf causing progressive movement of said material acrosssaidscreening element from shelf to shelf, and means for imparting tosaid screening element arecurrent motiOn in-,. eluding a horizontalcomponent characterized by abruptly initiatedhigh speed forward .move-.

ments to cause rearward discharge of some :of,

said material throughsaid slots-and by abrupt termination of said highspeedforward move ments todischarge some of said material from theforward edges of said shelves whereby said material-advances forwardlydown said screening element and is discharged forwardly therefrom.

4. In a screening apparatus, the combination of an inclined frame,a'plurality of substantially flat shelves extending transversely of saidframe each shelf being of a width substantially equal to the maximumgraded size of the material to be screened, said shelves being inclinedrearwardly at a small angle from the horizontal and spaced to provideunobstructed openings of predetermined width between said shelves, meansfor causing a mass of particulate material to pass progressively downsaid inclined frame from shelf to shelf whereby discrete particles ofsaid mass momentarily rest on said shelvesfand means for abruptly movingsaid frame to cause some of the particles on said shelves to passthrough the spaces between said shelves.

5. In a screening apparatus, a. screening element comprising an inclinedframe having a plurality of flat shelves of a width substantially equalto the maximum graded size of the material to be screened extendingtransversely thereof and having unobstructed slots of fixed predetermined height extending along the rear edge of each shelf, means forcausing a mass of particulate material-to pass progressively downwardlyover said screening element from shelf to shelf whereby discreteparticles of said mass come to rest momentarily on said shelves, andmeans for abruptly. moving said frame forwardly at recurrent intervalswhereby the inertia of said particles causes certain of said particlesto be disthereacross in step-like relation, said shelves combination; ofan inclined screening element having a p1,u-,-. rality of substantiallyflat shelveson whichthe material to be screened may momentarily rest,during passage over said screening element, said screening elementhaving'slotsofflxed predeter-j; minedwidth adjacent the rear edge ofeach being spaced apart vertically to provide unobstructed openings oisumcient size to permit the passage of undersized pieces of coal and theedgewise passage of flats therethrough but insuf- ,ilcientto permit thepassage of the remainder of said mass of coal, each of said shelves:being 'oi the'mass on each shelf onto the shelf below whereby said masspasses progressively down said 7' inclinedzscreening element from shelfto shelf for discharge forwardly therefromand additional-flatsandunder-sized pieces or coalcon- 'tainedtherein may come to restmomentarily on succeeding shelves for discharge rearwardly through saidopenings. m

1 7. An apparatus Iorseparating flats and under-sized pieces or .coalfrom I an otherwise graded-tq-size mass of coal comprising an inclinedscreening element including a plurality r substantially horizontallydisposed step members of a width substantially equal to the maximumgraded size of the material being treated,

said step members being vertically spaced apart to provide open slotstherebetween of a predetermined height less than the minimum graded sizeof the material being treated, and means for imparting to said screeningelement a re curring vmotion including an abruptly initiated andabruptly terminated, high speed, horizontal component 8. An apparatusfor separating flats and under-si'zed pieces of coal from an otherwisegraded-to-size mass of coal comprising a screen ing element including aplurality of step members, each 0! said step members being of a widthsuflicient tosupport only one row of particles of the maximum gradedsize and being spaced apart vertically from the adjacent step members toprovide unobstructed, slots therebetween of a height less than theminimum graded size or the material being treated, means for causing amass of particulated material to pass progressively downwardly over saidscreening element from step to step whereby discrete particles of saidmass come to rest momentarily on said steps, and means for abruptlymoving said screening element forwardly at recurring intervals wherebythe inertia of said particles causes those having at least one dimensionsmaller than the minimum graded size to be discharged from said stepsthrough said slots.

EDWARD B. MOORE.

